Clutch device



Jan. 12, 1932. R sHELDRlCK ET AL v 1,840,682

' CLUTCH DEVICE Fiied om 1o, 1929 sling. 1.

@fia 2 i: 4 y y 15 @L95 3 rmeff she/IHM .Le anal-J #ed 10 4 5 Inl/enfer Patented Jan. 12,A 1932 noennfnsnnrnnicx, or FAIRBANK, Ann LEONARD naar, or Tenencia, on'innro,

' CANADA Y Y f CLUTCH :envien l Application ined october 1o, .1929.; serial No. 398,776.

The principal objects of this invention are to provide a safety clutch adapted to carry a predetermined load but which will effectively prevent the transmission lof a greater load or T4i5 pressure than is desired, and to provide a clutch device particularly adapted foruse on starting cranks for internal combustion engines which will eliminate the possibilities of injury through the back-firing of` an enginei The principal feature of the invention consists in the novel construction and a'rrange- Y ment of a pair of clutch members andof the means for holding these in operating engage- K ment whereby a member rotatably -mounted 't1-5 upon a shaft and provided with `means on the end face for engaging a member rotat able with the Lshaft is held iii-operating con? tact with the member secured to the shaft by'a longitudinal spring pressure, Y

lin the accompanying drawingsyFig-ure l is a perspective view'of a motor car starting crank to Vwhich the present invention is iapplied. l

-Figure 2 is a longitudinal sectional view '25 showing the clutch members vin the position.

` of passing eachother. Y Y Figure 3 is an enlarged longitudinal sectional view showing the crank members in operating engagement. l

V'Figure 4 is alongitudinal `sectional View showin-g the crank members in the posi-tion of passing each other as shown in Figure12.

Safety clutches of various `kinds have beenv devised which permit the transmission of Cio certain predetermined mavimumy load, after which the clutch' members fail. The use of Va crank for starting internal combustion engines is Afrequently necessary and lmanypainful accidents result from: the

back firing o-f the engine. TheV invention hereindesoribed proposes to overcome these difficulties inthe vmatter `of clutches. f ,Y

The invention asshown consists ofashaft l which is provided with the usual cross pin 2 for engaging' the ratchet fend ofthe engine shaft. The other end of the shaft l is flattened for a portion of its length along one side and on this flattened portion is' mounted power from one member to anotherY up to a a cylindrical bloc-k 3. This 'block is provided y with a recess l Vin which is loosely secured 'a hardened steel ball .5. f lDiametjrically oppositeto vl'the recess 4 is arranged a larger recess 1-6in which is ar- 55 ranged 'a lar-ger ball'7. f f

"lhe crank 8 is provided with a circular hub end '9v which vis rotatably mounted upon the shaft 1 and preferably has a ball race 10 which engages the outer -perimeters of 'both 5@ the balls V5 and'f. f Y

A recess 11 is formed in the hub 9 in which is embedded a steel `bal-l 12,- p-referably Vof the same diameter as the ball '-7.

The balls 5 and '7 rest against the-end face 65 of th'eihirb 9 and upon the 'turning-of the hub 9 fthejball ,12 moves into engagement with the ball 7.' These balls project a sufficient dis-` tan'ceffrom their respective holding members thatwhen they move'into `contact they have 70 a substantial bearing angle which will cause, through the Yoperatioii of the crank, the turning ofthe shaft l against a Zcinsiderable pres- The' outer end` 13 of the shaft 1 is threaded 7'5 and enit is mounted anut ylll and a heavy coil spring 15 isarranged between the 'nut andthe hub 9 of the crank. Y l

The pressure of the-'spring 1'5 may be regulated in accordancev with'the load which is to 80 be moved bythe'operatifon of the crank mem-l ber and the spring is compressed 'until-the contacts lof the balls 7 and 12 are such as to ensure the turning of theshaft under lthe normal load. Such for instance, the lcom-Y 85 pression pressure in the startingfof an en-l :The adjustment of'it'he pressure ofV the spring '15 by. means' of the nutwillenable the user tofobtain lsuilicientpressure through the' 90 con-tact `ofthe balls 7 fand '1.2350 turn over the engine butin the event of a sudden excess :of pressure, such as created -by the back firing i of the'engine, the :spring will Oive way, permittingthe turning of the .shay 1,V inI aback- 95'* ward direction without causing the 'crank to turnbackward with fan injurious force;-` .Itwillof course be understood that a forward pressure beingzexertedby the 4operator and theA forceis applied through the en-v 10:0

gaging balls. When a greater resistance 0ccurs through the engine back firing, the ball contact of the block 3 forces the ball contact of the crank outwardly against the pressure o-f the spring l5 and passes same.

The arrangement of a ball contact in these two members is of very great importance as the steel balls have remarkable wearing qualities. rlheir conacts are only on a point and while the lin-es of force are such as to effectively operate the engine under the normal stresses, an excess stress will change the lines of force through the balls quite readily. Further it will be noted that the ball 5 forms a friction reducing contact between the members 3 and 9 at a point diametrically opposite the main clutch balls 7 and l2. Thus the pressure of the spring 15 does not set up an undue frictional resistance between the surfaces of the members 3 and 9, the actual adjacent surfaces thereof being spaced at all times. In this way the force that the conacting clutch balls 7 and 12 will transmit may be more definitely determined as would not be the case if the ball bearing 5 was omitted permitting lhe faces of the members 3 and 9 to rub in frictional contact which friction would vary in relation to the presence or absence of a lubricant therebetween.

The ball 5 is here shown of smaller size than the clutch balls 7 Aand 12, the smaller ball serving efliciently for bearing purposes and being less costly than would a larger ball. rIhe ball 5 however may if desired be of a size corresponding to the size of the ball 7 in which case it will not only serve as a bearing support as defined above but will co-operate with the ball 12 so that a uniform double-clutching action will be provided for each revolution of the member 9 on thelshaft.

The device while shown applied to a motor car crank can of course be readily applied to various other forms of clutch mechanisms where a safety limit of stress is desired.

The construction is very simple and it can be manufactured at very little cost in addition to that of the ordinary crank.

Vhat we claim as our invention is:

l. In a clutch device, the combination with a shaft, of a block keyed on the said shaft having a recess in its end face, a steel ball embedded in said recess and projecting beyond the end face, a member rotatably mounted on the shaft having a steel ball projecting from its end face adapted to engage the aforesaid steel ball upon rotation of the rotatable member on the shaft, and spring'means mounted on the shaft for holding the rotatable member toward the member secured to the shaft.

2. In a clutch device, the combination with a shaft, of a cylindrical block keyed to the shaft having a recess in its end face, a ball bedded in the recess projecting beyond the end face, a member rotatably mounted on the shaft having aball bedded in its end face adapted to engage the aforesaid ball to eect the turning of the shaft, a spiral spring encircling said shaft for holding said blocks and rotatable member together, and a nut threaded on the shaft for adjusting the compression of said spring. i

3. In a clutch device, a shaft, a cylindrical block rigidly mounted on said shaft, a ball mounted in the end face of said block and projecting therebeyond, a steel ball bedded in a recess in the end face of said block in dia- Vmetrically opposed relation to the aforesaid ball, a rotatable member mounted on the shaft having a ball race engaging the aforesaid balls, said latter member having a recess arranged in the path of said ball race, a ball bedded in said recess and adapted to engage one of the balls in the aforesaid block while the other ball engages the ball race in bearing contact, the contact of said balls being adapted to effect the turning of the shaft, a spiral spring coiled around the end of said shaft and exerting an end thrust against the. member rotatable on the shaft, a nut threaded on the end of said shaft adapted to adjust the pressure of said spring, and means secured to said rotatable member for turning it to turn th shaft.

l. An engine starting crank, comprising a shaft having a pin to engage the engine shaft ratchet, a block rigidly secured on said shaft and having a steel ball secured in its outer end face and projecting therefrom, a crank member having a cylindrical end rotatably mounted on said shaft, a steel ball bedded in the end face of said cylindrical part of the crank adapted to engage the end face of the fixed member on the shaft and to co-operate with the ball therein, a spiral spring encircling the outer end of the shaft and engaging the crank member and holding it toward the block secured on the shaft, and a nut threaded on the outer end of said shaft for adjusting the pressure of said spring.

5. In a clutch device, the combination with a shaft, a member` fixed to said shaft having an annular bearing surface and a raised projection extending above said bearing surface, a member rotatably mounted on said shaft having an annular bearing surface and a raised projection extending thereabove, the raised projections of said members being adapted to engage the annular bearing surfaces of said members andto contact with each other to effect the turning of the shaft, and spring means for holding the rotatable member to ward said fixed shaft member with the raised projections of said members in bearing contact with their respective annular bearing surfaces.

ROBERT SHELDRICK. LEONARD HEAP. 

